<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <div id="app">
    <div>
      <div
        style="display: inline-block"
        v-for="(item,index) in arr" 
        :key="index"
      >
        <input type="checkbox" 
        :value="item" 
        v-model="list"
        />
        <span>{{item}}</span>
      </div>
      <p>你选中的元素, 累加的值和为: {{sum}}</p>
    </div>
  </div>
  <script src="./vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
        arr: [9, 15, 19, 25, 29, 31, 48, 57, 62, 79, 87],
        list:[],
        sum:0
      },
     watch:{
        list(newVal){
            this.sum = this.list.reduce((sum,item)=>sum+item,0)
        }
     }
    })
  </script>
</body>

</html>